New Findings Span Earth and Mars
For years, scientists have painted a picture of a warmer, wetter Mars—one that hosted liquid water on its surface and a thicker atmosphere. A recent study led by geoscientists at the University of Arkansas strengthens this view by drawing a striking parallel between Earth’s geological formations and features observed on Mars. The research suggests that Mars may have had a vast ocean in the northern hemisphere, fed by ancient rivers that once carved channels and deltas across the planet’s landscape.
Bridging Earth and Mars with Delta Fans
The team focused on Aeolis Dorsa, a region in Utopia Planitia, where high-resolution images from NASA’s Mars Reconnaissance Orbiter reveal a complex network of channels and sediments. On Earth, similar river systems form delta fans as rivers slow near an open body of water. The researchers identified telltale signs—reminiscent of “backwaters”—that indicate rivers entering a broader basin. These backwater zones, which can extend across hundreds of kilometers, leave behind distinctive channel belts and sediment patterns that fossilize over time if the river dries up.
Earth’s Wedington Sandstone: A Living Analogy
To contextualize their Mars observations, the Arkansas team studied sandstone formations in northwestern Arkansas, formed by rivers about 300 million years ago. The Edington Sandstone formation, linked to an ancient river system that drained a vast regional basin, serves as a modern analogue. When exposure and erosion reveal ridges, the sedimentary history is preserved as inverted channels—where former riverbeds appear as raised ridges because finer sediments bury the coarser layers. That same inverted-ridge pattern has been spotted in Martian landscapes, suggesting similar processes once played out there.
Evidence for an Ocean in the Northern Lowlands
The researchers argue that the northern Martian lowlands likely hosted an ocean that drew in feeding rivers and formed mature delta systems. This hypothesis is supported by the morphology of Aeolis Dorsa and the presence of robust delta-like fans that resemble those formed where rivers meet seas here on Earth. The finding aligns with a broader consensus that Mars once possessed a denser atmosphere and liquid water, creating environments that could sustain long-lived bodies of water and, potentially, life.
Collaborative Effort and Peer Review
The study was led by Cory Hughes, a geosciences PhD candidate at the University of Arkansas, with collaboration from John B. Shaw, Anjali M. Fernandes, and Travis E. Swanson. Additional contributions came from Denison University and the Water Institute in Louisiana. The results were published in Geophysical Research Letters, reflecting a rigorous, cross-institutional effort to interpret orbital imagery through the lens of sedimentary geology.
Why This Matters for Mars Exploration
Beyond sketching Mars’s ancient climate, the work has implications for the planet’s potential to have once supported life. As Hughes notes, liquid water is a critical ingredient for life as we know it. The more compelling the evidence for standing bodies of water, the stronger the case that Mars offered habitable conditions at some point in its history. While Mars today is a dry, cold world, these findings remind us that the planet’s ancient past was radically different—a history that continues to shape how we search for signs of life beyond Earth.
The Way Forward
As planetary scientists gather more data from orbiters and landers, the Mars-Ocean hypothesis will be tested against new sedimentary evidence and possible in situ analyses. The Arkansas-led conference in January gathered experts from NASA’s Jet Propulsion Laboratory, the Planetary Science Institute, the University of Texas, and Stanford University to discuss analogues like the Edington Sandstone. Field observations of Martian analogues strengthen the interpretive framework scientists use to read the Red Planet’s ancient rivers and seas.
In the end, the idea that Mars once harbored an ocean near its northern plains is not merely a poetic image—it is a scientifically testable inference grounded in the earthbound logic of river deltas and inverted channels. As more data pours in from orbit and future missions, the case for a watery Mars becomes increasingly persuasive—and, with it, the tantalizing possibility that life could have found a foothold on the red world billions of years ago.
